For example, a washing machine described in Patent Document 1 has a dirt sensor such as a conductivity sensor for detecting a state of a washing liquid in a water tank, and executes control of a washing step based on a detection result of the state of the washing liquid such as dirt.
FIG. 4 is a vertically sectional view of the washing machine described in Patent Document 1.
As shown in FIG. 4, a transparency detection portion 63 for detecting a transparency of the washing liquid is provided in a drainage port of a water tank 62 accommodating a washing tank 61 in which an agitation blade 67 is arranged on a bottom. The transparency of the washing liquid detected by the transparency detection portion 63 is converted into a voltage signal by a first control portion 63a configured by an input unit, an output unit, and an arithmetic control unit. The first control portion 63a drives a motor 66 for driving the agitation blade 67 via a motor drive portion 65 based on this voltage signal.
Between the washing tank 61 and the water tank 62, a conductivity detection portion 64 for detecting conductivity of the washing liquid is provided. Based on the conductivity of the washing liquid detected by the conductivity detection portion 64, a second control portion 64a formed by an input unit, an output unit, and an arithmetic control unit determines a type of detergent. The second control portion 64a drives the motor 66 via the motor drive portion 65 based on the determined type of detergent.
The second control portion 64a extends a washing time in correspondence with the determined type of detergent.    Patent Document 1: Japanese Unexamined Patent Publication No. 63-154196